Elastic flat tread

ABSTRACT

The present invention is an elastic flat tread which can prevent an elastic solid from cracking even if the vehicle runs on a protruding object during traveling. For this purpose, the elastic flat tread is provided with any core ( 1, 11, 115 ) of a core ( 1, 11 ) attached to a link ( 6 ) and a core ( 115 ) attached to a metal plate (9A) which is attached to a link ( 8 ), and end portions ( 1   a   , 1   b   ; 11   a   , 11   h   ; 115   a   , 115   b ) in a longitudinal direction of the aforesaid any core ( 1, 11, 115 ) are bent toward the side not in contact with the ground.

TECHNICAL FIELD

The present invention relates to an elastic flat tread for an endlesscrawler belt, which is used for a hydraulic shovel, bulldozer, and otherconstruction equipment, and particularly, to an elastic flat tread withimprovements in the shapes and the materials of a core and an elasticsolid covering the core.

BACKGROUND ART

Conventional construction equipment such as hydraulic shovels andbulldozers with steel crawler belts being, attached has the disadvantageof damaging asphalt road surfaces when traveling on a public road on themove between work sites, and therefore increasing number of vehicles areequipped with rubber crawler belts recently.

The rubber crawler belts are formed by a number of core wires and coresembedded in rubber in an endless shape, but if problems such as a crackand peeling, of rubber occurs, it is difficult to repair them, whichnecessitates the replacement of the crawler belt to a new one, therebycausing the disadvantage of increasing user cost.

In order to overcome the foregoing disadvantage, elastic flat treadsformed by iron crawler plates with elastic solids such as rubber beingbonded thereto are used. Recently, an art is developed, in which a coreis embedded into an elastic solid to construct an elastic flat tread, aplurality of which are disposed in a longitudinal direction of a crawlerto thereby form an endless crawler belt.

As a prior art of an elastic flat tread, for example, Japanese PatentApplication Laid-open No. 7-152305 is known, which will be explainedwith reference to FIG. 53 and FIG. 54. In an elastic flat tread 140, aplanar core 120 is covered with an elastic solid 130 from the entireground-contacting side toward core end portions 121 and 121 in alongitudinal direction of the core 120 on the side not in contact withthe ground, and bonded thereto by vulcanization. The core 120 isfastened to a link 150 by bolts not illustrated. Numeral 132 is a bolthole for insertion of the bolt.

However, in the above elastic flat tread 140, as shown in FIG. 55,elastic solid end portions 131 are locally bent to thereby cause theconcentration of stress, when the elastic flat tread 140 runs on aprotruding object such as a rock or stone A and a curb stone of asidewalk not illustrated. As a result, the disadvantage of a crack Poccurring in the elastic solid end portion 131 is caused. This isbecause the core 120 is designed to have high rigidity so as not to bedeformed even if the vehicle weight W of construction equipment isexerted on the elastic flat tread 140 via a lower roller 145 and a link150.

Meanwhile, even the elastic solid 130 with higher rigidity in nature haslower rigidity than that of the core 120. Consequently, when running ona protruding object such as a rock or stone A and a curb stone of a sidewalk, so long as the protruding object does not escape therefrom,distortion concentrates on the elastic solid 130 due to the differencein rigidity between the core 120 and the elastic solid 130, therebycausing the crack P in the elastic solid end portion 131 shown in FIG.55.

Further, the head portions of bolts fastening the core 120 and the link150 contact the elastic solid 130, thus causing the disadvantage that acrack and peeling occur at the bolt insertion holes 132.

DISCLOSURE OF THE INVENTION

The present invention is made in view of the disadvantages of the priorart, and its object is to provide an elastic flat tread capable ofpreventing an elastic solid from cracking when a vehicle runs on orcollides with a rock or a stone, or a curb stone of a sidewalk duringtraveling.

In order to attain the above object, a first aspect of an elastic flattread according to the present invention is an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side, andcharacterized in that

the aforesaid core is any core of a core attached to the aforesaid linkand a core attached to a metal plate which is attached to the aforesaidlink, and in that

end portions in a longitudinal direction of the aforesaid any core arebent toward the side not in contact with the ground.

According to the above structure, even if the vehicle runs on orcollides with a protruding object such as a rock or stone, or a curbstone of a sidewalk, since the end portions in a longitudinal directionof the core are bent toward the side not in contact with the ground, therock or stone escapes from the elastic solid end portion formed alongthe bent portion of the core, thus making it possible to avoid localconcentration of stress on the elastic solid. When the angle of bend ofthe core end portion is made larger, even if the elastic solid endportion formed along the bent portion collides with a curb stone of asidewalk, local concentration of stress on the elastic solid can beavoided. The angle of bend of core end portion is appropriately set inthe range of 10 degrees to 90 degrees, and the angle of bend of the coreend portion is set in consideration of the weights of various kinds ofmodels small to large in size, the sizes of the elastic flat treads, thelengths in the longitudinal direction of the cores, and the like. Forexample, in a small-sized model which frequently operates in a workingsite with many small rocks and stones, the angle of bend of the core endportion may be made smaller, and in a large-sized model which frequentlyoperates in a working site with many large rocks and stones, the angleof bent of the core end portion may be larger. Consequently, even if thevehicle runs on a protruding object such as a rock or stone, or a curbstone of a sidewalk during traveling, a crack does not occur in theelastic solid end portion, thus increasing durability of the elasticflat tread.

A second aspect of the invention is characterized in that at least onelayer of cable layers is provided inside the aforesaid elastic solid,under the aforesaid any core, near an end portion in a longitudinaldirection of the aforesaid any core, in the structure of the firstaspect of the invention.

According to the above structure, in addition to the operational effectsof the first aspect of the invention, the cable layer is embedded nearthe end portion in a longitudinal direction of the core, therebyincreasing the rigidity at this portion, which eliminates the occurrenceof a crack in the elastic solid even if the elastic solid end portionruns on or collides with an protruding object such as a rock or stone,or a curb stone of a sidewalk. Consequently, durability of the elasticflat tread is improved, which makes the elastic flat tread useful toconstruction equipment operating in various working sites.

A third aspect of the invention is characterized in that a direction inwhich cable wires of the aforesaid cable layers are placed is either oneof the parallel and diagonal directions relative to the longitudinaldirection of the aforesaid any core, or the combination of twodirections or more selected from the parallel and diagonal directions,in the structure of the second aspect of the invention.

According to the above structure, the elastic solid is strengthened bythe cable layer with the direction of the cable wires being either oneof or two or more of the parallel and diagonal directions relative tothe longitudinal direction of the core, and therefore a crack does notoccur in the elastic solid even if the elastic solid end portion runs onor collides with a protruding object such as a rock or stone, or a curbstone of a sidewalk. Consequently, durability of the elastic flat treadis improved, which makes the elastic flat tread useful to constructionequipment operating in various working sites.

A fourth aspect of the invention is characterized by including asynthetic resin member which is placed near the end portion in thelongitudinal direction of the aforesaid any core, and which is fixed tothe aforesaid elastic solid, in the structure of the first aspect of theinvention.

According to the above structure, if the synthetic resin member with asmaller friction coefficient is fixed to the elastic solid, a rock or astone slips and escapes, even if the synthetic resin member runs on aprotruding object such as a rock or stone, or a curb stone of asidewalk, thereby making it possible to avoid local concentration ofstress. Further, by using the synthetic resin member with higherrigidity than the elastic solid, rigidity around the core end portioncan be increased. Consequently, even if the elastic flat tread runs on aprotruding object such as a rock or a stone, or a curb stone of asidewalk during traveling, a crack does not occur, thus improvingdurability of the elastic flat tread.

A fifth aspect of the invention is characterized in that the aforesaidelastic solid is integrally formed by elastic solids with differenthardnesses, in which the hardness at a portion in contact with theaforesaid any core is the highest and the hardness sequentially lowerstoward the ground-contacting side, in the structure of the first aspectof the invention.

According to the aforesaid structure, in addition to the operationaleffects of the fist aspect of the invention, the elastic solid with ahigher hardness is strong against an unbalanced load caused bydeflection or the like, but provides poor riding quality and less wearresistance on the other hand, and thus the elastic solid is designed tohave the highest hardness at the portion nearest to the core. To makethe hardness sequentially lower toward the ground-contacting side, theelastic solid having a lower hardness is provided on theground-contacting side in consideration of riding quality and wearresistance. Accordingly, even if the elastic solid end portion runs on aprotruding object such as a rock or stone, or a curb stone of asidewalk, a crack does not occur in the elastic solid end portion, thusimproving durability of the elastic flat tread.

A sixth aspect of the invention is characterized in that the aforesaidany core is formed of spring steel, in the structure of the first aspectof the invention.

According to the above structure, as in the structure of the firstaspect of the invention, the end portions in the longitudinal directionof the core formed of spring steel are bent toward the side not incontact with the ground, and therefore even if the elastic solid endportion formed along the bent portion of the core runs on a protrudingobject such as a rock or stone, or a curb stone of a sidewalk, the coreformed of spring steel is displaced upward, thereby making it possibleto avoid local concentration of stress on the elastic solid end portion.Consequently, even if the elastic solid end portion runs on a protrudingobject such as a rock or stone, or a curb stone of a sidewalk, a crackdoes not occur, thus improving durability of the elastic flat tread.

A seventh aspect of the invention is characterized in that the ratiobetween a height h, which is from a mounting surface for the aforesaidlink up to a tip end in a height direction of the end portion in thelongitudinal direction of the aforesaid any core, and a link pitch Lp is0.05≦h/Lp≦0.25, in the structure of the first aspect of the invention.

An eighth aspect of the invention is characterized in that the ratiobetween a height h, which is from a mounting surface for the aforesaidlink up to a tip end in a height direction of the end portion in thelongitudinal direction of the aforesaid any core, and a height H of theelastic flat tread is 0.08≦h/H≦0.50, in the structure of the firstaspect of the invention.

A ninth aspect of the invention is characterized in that the ratiobetween a width W1 of the aforesaid any core, and a width W2 of a tipend in the longitudinal direction of the aforesaid any core is0.5<W2/W1≦0.9, in the structure of the first aspect of the invention.

In the above seventh aspect through the ninth aspect of the invention,the dimensional ratio of the core and the like of the first aspect ofthe invention is specified, and as in the operational effects of thefirst aspect of the invention, a crack does not occur in the elasticsolid end portion, thus improving durability of the elastic flat tread.

A tenth aspect of the invention is, in an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side,characterized in that

the aforesaid core is any core of a core attached to the aforesaid linkand a core attached to a metal plate which is attached to the aforesaidlink, and is characterized in that

at least one layer of cable layers is provided inside the aforesaidelastic solid, under the aforesaid any core, near an end portion in alongitudinal direction of the aforesaid any core.

The above structure corresponds to the structure of the second aspect ofthe invention of which core is not bent, and thus the same operationaleffect as in the second aspect of the invention can be obtained.

An eleventh aspect of the invention is characterized in that a directionin which cable wires of the aforesaid cable layers are placed is eitherone of the parallel and diagonal directions relative to the longitudinaldirection of the aforesaid any core, or the combination of twodirections or more selected from the parallel and diagonal directions,in the structure of the tenth aspect of the invention.

The above structure corresponds to the structure of the third aspect ofthe invention, and the same operational effects as in the thirdinvention can be obtained.

A twelfth aspect of the invention is, in an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side, ischaracterized in that

the aforesaid core is any core of a core attached to. the aforesaid linkand a core attached to a metal plate which is attached to the aforesaidlink, and characterized by further including

a synthetic resin member placed near an end portion in a longitudinaldirection of the aforesaid any core and fixed to the aforesaid elasticsolid.

The above structure corresponds to the structure of the fourth aspect ofthe invention of which core is not bent, and thus the same operationaleffects as in the fourth invention can be obtained.

A thirteenth aspect of the invention is, in an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side,characterized in that

the aforesaid core is any core of a core attached to the aforesaid linkand a core attached to a metal plate which is attached to the aforesaidlink, and characterized in that

the aforesaid elastic solid is integrally formed by elastic solids withdifferent hardness, in which the hardness at a portion in contact withthe aforesaid any core is the highest and the hardness sequentiallylowers toward the ground-contacting side.

The above structure corresponds to the structure of the fifth aspect ofthe invention of which core is not bent, and thus the same operationaleffects as in the fifth aspect of the invention can be obtained.

A fourteenth aspect of the invention is, in an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side, and ischaracterized in that

the aforesaid core is any core of a core attached to the aforesaid linkand a core attached to a metal plate which is attached to the aforesaidlink, and characterized in that

the aforesaid any core is formed of spring steel.

The above structure corresponds to the structure of the sixth aspect ofthe invention of which core is not bent, and the same operationaleffects can be obtained as in the sixth aspect of the invention.

A fifteenth aspect of the invention is, in an elastic flat tread havinglinks of which end portions are connected to the adjacent end portionsin a traveling direction of a crawler with a pin, and a core coveredwith an elastic solid at least on the ground-contacting side,characterized in that

end portions in a longitudinal direction of the aforesaid core are benttoward the side not in contact with the ground, and characterized inthat

end portions of the aforesaid elastic solid are protruded outwardrelative to the tip ends of the end portions in the longitudinaldirection of the aforesaid core.

According to the above structure, when the vehicle runs on or collideswith a protruding object such as a rock or stone, or a curb stone of asidewalk during traveling, the end portion in the longitudinal directionof the core is bent toward the side not in contact with the ground, thusmaking it possible to avoid local concentration of stress on the elasticsolid as a result that the rock or the stone escapes from the elasticsolid end portion formed along the bent portion of the core. Since theelastic solid end portion formed along the bent portion of the core isprotruded outward from the end portion of the core, therefore in theelastic solid end portion, an impact caused by the collision with anprotruding object such as a rock or stone, or a curb stone of a sidewalkcan be lessened. Accordingly, even if the vehicle runs on or collideswith a protruding objet such as a rock or stone, or a curb stone of asidewalk during traveling, a crack does not occur in the elastic solidend portion, thus improving durability of the elastic flat tread.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view of a first embodiment of an elastic flattread according to the present invention;

FIG. 2 is a view seen from the arrow Y in FIG. 1;

FIG. 3 is a view explaining the traveling state of an elastic flat treadin FIG. 1;

FIG. 4 is an explanatory view of an example in which an a core iscovered with and bonded to an elastic solid from the ground-contactingside to the side not in contact with the ground;

FIG. 5 is an explanatory view of a second embodiment of the elastic flattread according to the present invention;

FIG. 6 is a view seen from the arrow X in FIG. 5;

FIG. 7 is a view explaining the traveling state of the elastic flattread in FIG. 5;

FIG. 8 is an explanatory view of an example in which the core in FIG. 5is covered with and bonded to the elastic solid from theground-contacting side to the side not in contact with the ground;

FIG. 9 is a view explaining a first example of the core according to thepresent invention;

FIG. 10 is a view explaining a second example of the core according tothe present invention;

FIG. 11 is a view explaining a third example of the core according tothe present invention;

FIG. 12 is a view explaining a fourth example of the core according tothe present invention;

FIG. 13 is a view explaining a fifth example of the core according tothe present invention;

FIG. 14 is an explanatory view of the core in FIG. 13 being covered withand bonded to the elastic body;

FIG. 15 is a view seen from the arrow W in FIG. 14;

FIG. 16 is a view explaining another elastic flat tread according to thepresent invention;

FIG. 17 is an explanatory view of an essential part of a thirdembodiment of the elastic flat tread according to the present invention;

FIG. 18 is an explanatory view of the essential part, in which theelastic flat tread in FIG. 17 is seen from the ground-contacting side;

FIG. 19 is a diagram regarding the durability evaluation of the elasticflat tread in FIG. 17;

FIG. 20 to FIG. 24 show examples of the core shapes applied to the thirdembodiment of the elastic flat tread of the present invention;

FIG. 20 is an explanatory view of the essential part of a core of whichend portion is bent in two stages; FIG. 21 is an explanatory view of theessential part of another core of which end portion is bent in twostages; FIG. 22 is an explanatory view of the essential part of a coreof which end portion is formed with a predetermined curvature radius;FIG. 23 is an explanatory view of the essential part of a core of whichend portion is formed with a different curvature radius from that inFIG. 22; and FIG. 24 is an explanatory view of the essential part of acore of which end portion is formed by a plurality of curved surfaces;

FIG. 25 is an explanatory view of a fourth embodiment of the elasticflat tread according to the present invention;

FIG. 26 is a view seen from the arrow V in FIG. 25;

FIG. 27 is a sectional view taken along the 27—27 line in FIG. 25;

FIG. 28 is an explanatory view of an application of the fourthembodiment of the elastic flat tread according to the present invention;

FIG. 29 is an explanatory view of a fifth embodiment of the elastic flattread according to the present invention;

FIG. 30 is a view seen from the arrow U in FIG. 29;

FIG. 31 is an explanatory view of a sixth embodiment of the elastic flattread according to the present invention;

FIG. 32 is a view seen from the arrow T in FIG. 31;

FIG. 33 is an explanatory view of an application of the sixth embodimentof the elastic flat tread according to the present invention;

FIG. 34 is an explanatory view of a seventh embodiment of the elasticflat tread according to the present invention;

FIG. 35 is a sectional view taken along the 35—35 line in FIG. 34;

FIG. 36 is an explanatory view of an eighth embodiment of the elasticflat tread according to the present invention;

FIG. 37 is an explanatory view of an application of the eighthembodiment of the elastic flat tread according to the present invention;

FIG. 38 is an explanatory view of a ninth embodiment of the elastic flattread according to the present invention;

FIG. 39 is an explanatory view of an application of the ninth embodimentof the elastic flat tread according to the present invention;

FIG. 40 is an explanatory view of a tenth embodiment of the elastic flattread according to the present invention;

FIG. 41 is a view seen from the arrow S in FIG. 40;

FIG. 42 is a view explaining a traveling state of the elastic flat treadin FIG. 40;

FIG. 43 is an explanatory view of an eleventh embodiment of the elasticflat tread according to the present invention;

FIG. 44 is a view seen from the arrow R in FIG. 43;

FIG. 45 is an explanatory view of an application of the eleventhembodiment of the elastic flat tread according to the present invention;

FIG. 46 is an explanatory view of another application of the eleventhembodiment of the elastic flat tread according to the present invention;

FIG. 47 is an explanatory view of a twelfth embodiment of the elasticflat tread according to the present invention;

FIG. 48 is an explanatory view of the elastic flat tread in FIG. 47 seenfrom the ground-contacting side;

FIG. 49 is a sectional view taken along the 49—49 line in FIG. 48;

FIG. 50 is an explanatory view of a thirteenth embodiment of the elasticflat tread according to the present invention;

FIG. 51 is an explanatory view of the elastic flat tread in FIG. 50 seenfrom the ground-contacting side;

FIG. 52 is a sectional view taken along the 52—52 line in FIG. 51;

FIG. 53 is a plan view of a conventional elastic flat tread seen fromthe ground-contacting side;

FIG. 54 is a view seen from the arrow Z in FIG. 53; and

FIG. 55 is a view explaining a problem occurring to the conventionalelastic flat tread flat during traveling.

BEST MODE FOR CARRYING OUT THE INVENTION

An elastic flat tread according to the present invention will beexplained below with reference to FIG. 1 through FIG. 52. Initially, afirst embodiment of the elastic flat tread will be explained withreference to FIG. 1 through FIG. 4.

As FIG. 1 and FIG. 2 show, a core 1 is covered with and bonded to anelastic solid 2 such as rubber. A tread which is formed by the core 1covered with and bonded to the elastic solid 2 is called an elastic flattread 3. Bolts not illustrated are inserted into bolt insertion holes 2c provided in the elastic solid 2, thereby attaching the elastic flattread 3 to a link 6. A number of elastic flat treads 3 are disposed in atraveling direction of a crawler, and end portions of the links 6adjacent to each other are connected to each other with pins 6 a to forman endless crawler belt. A lower roller 5 attached to a vehicle body notillustrated abuts to the tread surface of the link 6 to thereby rotate.The weight of the vehicle body is exerted on the core 1 via the lowerroller 5 and the link 6. Consequently, the core 1 is made of a materialwith high rigidity so as not to be deformed. Core end portions 1 a and 1b are bent toward the side not in contact with the ground. An angle ofbend α1 in this case is set at, for example, 45 degrees.

The operation in FIG. 1 and FIG. 2 will be explained based on FIG. 3. AsFIG. 3 shows, when the vehicle runs on, or collides with a protrudingobject such as a rock A or a curb stone during traveling, the endportion 1 b in a longitudinal direction of the core 1 is bent toward theside not in contact with the ground, thus allowing, the rock A to escapein the X direction from an elastic solid end portion 2 b formed along abent portion of the core 1. As a result, the elastic solid 2 can avoidthe local concentration of stress at the end portion 2 b.

In the first embodiment, the angles of bend α1 of the core end portions1 a and 1 b are set at 45 degrees, but they can be appropriately set inthe range of 10 degrees to 90 degrees. Specifically, the angles of bendα1 of the core end portions la and 1 b are set in consideration of theweights of various types of vehicles which are small to large in size,the size of the elastic flat tread 3, and the dimension of the core 1 inits longitudinal direction. For example, in a small-sized vehicle whichis frequently operated in a work site with a large number of small rocksand stones, it is suitable to reduce the angles of bend α1 of the coreend portions 1 a and 1 b, while in a large-sized vehicle which isfrequently operated in a work site with a large number of large rocksand stones, it is suitable to increase the angles of bend α1 of the coreend portions 1 a and 1 b. Thus, even if the vehicle runs on a protrudingobject such as the rock A and a curb stone, a crack does not occur inthe elastic solid end portions 2 a and 2 b, thereby increasingdurability of the elastic flat tread 3.

An elastic flat tread 3A shown in FIG. 4 is an example in which thesides of the core end portions 1 a and 1 b, which are not in contactwith the ground, are also covered with and bonded to end portions 2 eand 2 d of the elastic solid 2. In the other points, the elastic flattread 3A has the same structure and effects as the elastic flat tread 3in FIG. 1, therefore omitting the explanation thereof .

According to the structure in FIG. 4, compared to the elastic flat tread3 in the first embodiment in FIG. 1, the core 1 is covered with andbonded to the elastic solid 2 up to the sides not in contact with theground, thus preventing the core 1 and the elastic solid 2 from peelingaway.

Subsequently, a second embodiment of the elastic flat tread will beexplained with reference to FIG. 5 through FIG. 8.

As FIG. 5 and FIG. 6 show, a core 10 is covered with and bonded to anelastic solid 20 such as rubber. A tread which is formed by the core 10covered with and bonded to the elastic solid 20 is called an elasticflat tread 3B. Bolts not illustrated are inserted into bolt insertionholes 20 c provided in the elastic solid 20 to thereby attach theelastic flat tread 3B to the link 6. A number of elastic flat treads 3Bare disposed in a traveling direction of a crawler, and end portions ofthe links 6 adjacent to each other are connected to each other with pins6 a to thereby form an endless crawler belt. The lower roller 5 attachedto the vehicle body not illustrated abuts to the tread surface of thelink 6 to thereby rotate. The weight of the vehicle body is exerted onthe core 10 via the lower roller 5 and the link 6. Consequently, thecore 10 is made of a material with high rigidity so as not to bedeformed. Core end portions 10 a and 10 b are bent toward the side notin contact with the ground. An angle of bend α2 in this case is set at90 degrees.

The operation in FIG. 5 and FIG. 6 will be explained based on FIG. 7.Even if the vehicle collides with, or runs on a curb stone of a sidewalkor the like during traveling, since the end portion 10 b in alongitudinal direction of the core 10 is bent toward the side not incontact with the ground, the elastic solid 20 can avoid the localconcentration of stress at an end portion 20 b owing to the elasticeffect of the elastic solid end portion 20 b formed along the bentportion of the core 10. As a result, a crack does not occur in theelastic solid end portions 20 a and 20 b, thereby increasing durabilityof the elastic flat tread 3B. As in the first embodiment, the angles ofbend α2 of the core end portions 10 a and 10 b are appropriately set inthe range of 10 degrees to 90 degrees.

An elastic flat tread 3C shown in FIG. 8 is an example in which thesides of the core end portions 10 a and 10 b, which are not in contactwith the ground, are covered with and bonded to end portions 20 e and 20d of the elastic solid 20. In the other points, the elastic flat tread3C has the same structure and effects as the elastic flat tread 3B inFIG. 5, therefore omitting the explanation thereof.

According to the structure in FIG. 8, compared to the elastic flat tread3B in the second embodiment in FIG. 5, the core 10 is covered with andbonded to the elastic solid 20 up to the sides not in contact with theground, thus preventing the core 10 and the elastic solid 20 frompeeling away.

Next, the shapes of the cores according to the elastic flat tread of thepresent invention will be explained with reference to FIG. 9 throughFIG. 13. Only the end portions on one side of the cores are shown inFIG. 9 through FIG. 13, and it is noted that the end portions on bothsides are formed in the same shape.

FIG. 9 shows the core 1 shown in the first embodiment in FIG. 1, and theangle of bend α1 at the core end portion 1 bis set at 45 degrees. FIG.10 shows the core 10 shown in the second embodiment in FIG. 5, and theangle of bend α2 at the core end portion 10 b is set at 90 degrees.

A core 30A in FIG. 11 shows an example in which a square end portion 30a is formed. A core 30B in FIG. 12 shows an example in which a circularend portion 30 b is formed. A core 30D in FIG. 13 shows an example inwhich an end portion 30 d in a shape of the bottom of a ship is formed.

With the core 30D shown in FIG. 13 cited as an example, the structure ofthe covering of the elastic solid will be explained. Since the coresshown in FIG. 9 through FIG. 12 have the same structure, the explanationthereof will be omitted. As FIG. 14 and FIG. 15 show, an elastic solid31 covers and bonds to the core 30D from the ground-contacting side toan end portion 31 b on the side not in contact with the ground. In sucha elastic flat tread, the same effects can be obtained as in theembodiments shown in FIG. 1 and FIG. 5.

FIG. 16 shows a plan view of another elastic flat tread according to thepresent invention, in which an elastic solid 32 covers and bonds to acore 30E. An end portion 30 e of the core 30E is formed to be square,and corner portions 32 a and 32 a are formed at the end portion of theelastic solid 32 for covering and bonding to the core end portion 30 e.As a result that the corner portions 32 a and 32 a are formed, a crackand the like do not occur in the elastic solid 32 even if the elasticflat tread collides with, or runs on a protruding object such as a rockand stone.

Subsequently, a third embodiment of the elastic flat tread will beexplained with reference to FIG. 17 through FIG. 24.

As FIG. 17 and FIG. 18 show, in the elastic flat tread 33, a core 11other than a link mounting surface 6 b is covered with and bonded to anelastic solid 22 such as rubber. Only one side of the elastic flat tread33 is illustrated, and the other side is omitted, since the other sideis in a form symmetrical with the one side. In the elastic flat tread33, the link 6 (See FIG. 1) is attached on the link mounting surface 6 bwith bolts being inserted into bolt insertion holes 22 c provided in theelastic solid 22. As in the first embodiment, the elastic flat treads 33form an endless crawler belt.

The core 11 is made of a material with high rigidity so as not to bedeformed, and the end portion 11 a is bent toward the side not incontact with the ground at a predetermined angle of bend α. The core endportion 11 a is formed in such a shape that tapers toward a tip end 11 cin a longitudinal direction of the core 11. In the third embodiment,chamfered portions 11 d are formed on the ground-contacting side at bothends in a lateral direction of the core 11, but they may be omitted.

The characteristics of the elastic flat tread 33 according to the abovestructure will be explained. FIG. 19 shows the relationship between theangle of bend α of the core end portion 11 a, and the durabilityevaluation index regarding a crack occurrence in the elastic solid endportion 22 a. Here, the durability evaluation index of the angle of bendα=0° is the data of a conventional elastic flat tread, which is almostthe same as an elastic flat tread 140 shown in FIG. 53. As is obviousfrom FIG. 19, the core end portion 11 a is bent toward the side not incontact with the ground, thereby increasing the durability against acrack occurrence in the elastic solid end portion 22 a.

Consequently, the durability increases at the angle of bend α>0° ascompared with the prior art (the angle of bend α=0°), and in obtainingexcellent durability, 10°≦the angle of bend α≦90° is preferable.Further, in order to achieve a suitable thickness for an elastic solidthickness T1 shown in FIG. 17, it is more preferable that the angle ofbend α≦15°, specifically, 15°≦the angle of bend α≦90°. Meanwhile, inorder to reduce the concentration of stress occurring at the elasticsolid end portion 22 a near a bent portion 11 e (See FIG. 17), it ismore preferable that the angle of bend α≦45°, specifically, 15°≦theangle of bend α≦45°. From the above, in obtaining extremely excellentdurability, it is still more preferable that 15°≦the angle of bendα≦45°.

As a factor of the durability evaluation index, the relationship withthe angle of bend α is explained, but other factors may be used. Forexample, the explanation can be made by the relationship between aheight h shown in FIG. 17, specifically, the height h from the linkmounting surface 6 b up to a tip end 11 b in a height direction of thecore end portion 11 a, and a link pitch, specifically, the distancebetween axes of the pins 6 a and 6 a (See FIG. 1) for connecting thelinks 6 and 6 (See FIG. 1) adjacent in a fore-and-aft direction of thecrawler traveling direction (hereinafter called a link pitch Lp). Inthis case, an excellent durability evaluation index can be obtained when0.05≦h/Lp≦0.25. Further, in order to achieve an appropriate thicknessfor the elastic solid thickness T1, it is more preferable thath/Lp≧0.09. Meanwhile, in order to reduce the adverse possibility thatinterference may occur between the elastic flat tread 33 and componentsaround the vehicle body or the like, it is more preferable thath/Lp≦0.13. Accordingly, it is a still more preferable condition that0.09≦h/Lp≦0.13.

Further, as another factor of the durability evaluation index, therelationship between the above height h and a height H of the elasticflat tread 33 shown in FIG. 17 may be suitable. In this case, apreferable durability evaluation index can be obtained when0.08≦h/H≦0.5. Further, in order to achieve an appropriate thickness forthe elastic solid thickness T1, it is more preferable that h/H≧0.16.Meanwhile, in order to reduce the adverse possibility of theinterference as in the above, it is more preferable that h/H≦0.23.Accordingly, it is a still more preferable condition that 0.16≦h/H≦0.23.

Further, as still another factor of the durability evaluation index, therelationship between a width W1 of the core 11 shown in FIG. 18 and awidth W2 of the tip end 11 c in a longitudinal direction of the core 11may be suitable. In this case, a preferable durability evaluation indexcan be obtained when 0.5≦W2/W1≦0.9. Further, in order to reduce theconcentration of stress occurring at the elastic solid end portion 22 anear the tip end 11 c in the longitudinal direction when the vehicleruns on a protruding object such as a rock and stone, it is morepreferable that W2/W1≧0.65. Meanwhile, in order to reduce theconcentration of stress occurring at the elastic solid end portion 22 anear a corner portion 11 g of the core end portion 11 a when the vehicleruns on a protruding object, it is more preferable that W2/W1≦0.8.Accordingly, it is a still more preferable condition that0.65≦W2/W1≦0.80.

Regarding the core 11 in the third embodiment, the shapes other thanthat in FIG. 17 will be explained with reference to FIG. 20 to FIG. 24.In the core 11 in FIG. 20, the core end portion 11 a is bent at twokinds of angles of bend α3 and α4, and α3>α4. In the core 11 in FIG. 21,the core end portion 11 a is bent at two kinds of angles of bend α5 andα6, and α5<α6. FIG. 20 and FIG. 21 show the examples in which the coreend portion 11 a is bent in two stages, but the core end portion 11 amay be bent in three stages or more as necessary. The core 11 in FIG. 22has a structure in which the core end portion 11 a is formed with aradius of curvature R1 and the core end portion 11 a is in contact withthe core 11. The core 11 in FIG. 23 shows the example in which the coreend portion 11 a is formed with a radius of curvature R2 and the coreend portion 11 a forms the bent portion 11 e. The core 11 in FIG. 24shows the example in which the core end portion 11 a is formed by aplurality of curved surfaces. The core end portion 11 a in FIG. 24 maybe a combination of curved surfaces and flat surfaces.

Next, a fourth embodiment of the elastic flat tread will be explainedwith reference to FIG. 25 through FIG. 27.

An elastic flat tread 3F is formed by a core 40 covered with and bondedto an elastic solid 50 such as rubber. The elastic flat tread 3F isfastened to the link 6 by bolts not illustrated being inserted into boltinsertion holes 50 c provided in the elastic solid 50. An end portion 50b of the elastic solid 50 is in a form protruding outward relative to anend portion 40 b of the core 40. A cable layer 60A is placed inside theelastic solid 50 and under the core 40.

As FIG. 26 and FIG. 27 show, the cable layer 60A consisting of aplurality of cable wires parallel with the core 40 is placed under thecore 40.

FIG. 25 shows the cable layer 60A embedded in the elastic solid 50 onlyon one side, specifically, only on the outer side of the vehicle, but itmay be provided on both sides. The length of the portion of an endportion 50 a of the elastic solid 50, which is protruded outward from anend portion 40 a of the core 40, and the length of the portion of theend portion 50 b of the elastic solid 50, which is protruded outwardfrom the end portion 40 b of the core 40 may be symmetric. The lengths?of the portion protruded outward may be asymmetric as in FIG. 25. Theabove is appropriately designed in consideration of the weights ofvarious model from small to large in size, the size of the elastic flattread 3 and the like.

The operation of FIG. 25 through FIG. 27 will be explained. As a resultthat the cable layer 60A is embedded near the end portion 40 b in thelongitudinal direction of the core 40, rigidity increases in thisportion. Thereby, even if the elastic solid end portion 50 b runs on orcollides with a protruding object such as a rock and stone, a curb stoneof a sidewalk and the like, a crack does not occur at the elastic solidend portion 50 b. Further, since the elastic solid end portion 50 b isprotruded outward relative to the end portion 40 b of the core 40, evenif the elastic solid end portion 50 b collides with a protruding objectsuch as a curb stone of a sidewalk or the like during traveling, theimpact caused by the collision with the protruding object can belessened. As described above, even if the elastic flat tread 3F runs onor collides with a protruding object such as a curb stone of a sidewalkor the like during traveling, a crack does not occur at the elasticsolid end portion 50 b, thus increasing durability of the elastic flattread 3F.

As an application of the fourth embodiment, the cable layer 60A may beprovided in the elastic flat tread 33 (See FIG. 17). For example, asFIG. 28 illustrates, in an elastic flat tread 33F, the cable layer 60Ais embedded inside an end portion 22 d of the elastic solid 22 under anend portion 11 h in the longitudinal direction of the core 11. Accordingto the above structure, as in the above, durability of the elastic flattread 33F is increased.

A fifth embodiment of the elastic flat tread will be explained withreference to FIG. 29 and FIG. 30.

An elastic flat tread 3E is formed by the core 40 covered with andbonded to the elastic solid 50 such as rubber. The elastic flat tread 3Eis attached to the link 6 by bolts not illustrated being inserted intothe bolt insertion holes 50 c provided in the elastic solid 50. The endportion 50 b of the elastic body 50 is formed to protrude outwardrelative to the end portion 40 b of the core 40. A cable layer 60B isdiagonally placed inside the elastic solid 50 and under the core 40.FIG. 29 and FIG. 30 show only one layer of the cable layer 60B, but theconfiguration with a plurality of layers of the cable layers 60B may besuitable.

FIG. 29 shows the cable layer 60B embedded in the elastic solid 50 onlyon one side, but it may be provided on both sides. The length of theportion of the end portion 50 a of the elastic solid 50, which isprotruded outward from the end portion 40 a of the core 40, and thelength of the portion of the end portion 50 b of the elastic solid 50,which is protruded outward from the end portion 40 b of the core 40 maybe symmetric. The lengths of the portions protruded outward may beasymmetric as in FIG. 29.

The operation in FIG. 29 and FIG. 30 will be explained. The cable layer60B consisting of a plurality of cable wires diagonally placed isembedded near the end portion 40 b in the longitudinal direction of thecore 40. As the result, rigidity increases in the area near the portionwhere it is embedded, and thus even if the elastic solid end portion 50b runs on, or collides with a protruding object, a crack does not occurat the elastic solid end portion 50 b. Further, since the elastic solidend portion 50 b is protruded outward relative to the end portion 40 bof the core 40, even if the elastic solid end portion 50 b collides witha curb stone of a sidewalk or the like during traveling, the impactcaused by the collision with the curb stone or the like can be lessened.As the result, as in the above embodiment, a crack does not occur at theelastic solid end portion 50 b, thus increasing durability of theelastic flat tread 3E.

A sixth embodiment of the elastic flat tread will be explained withreference to FIG. 31 and FIG. 32.

An elastic flat tread 3G is formed by the core 40 covered with andbonded to the elastic solid 50 such as rubber. The elastic flat tread 3Gis attached to the link 6 by bolts not illustrated being inserted intothe bolt insertion holes 50 c provided in the elastic solid 50.

The end portion 50 b of the elastic body 50 is formed to protrudeoutward relative to the end portion 40 b of the core 40. Two layers ofcable layers 60C are placed inside the elastic solid 50 and under thecore 40. The first cable layer 60C is a cable layer with a plurality ofcable wires being diagonally placed. A plurality of cable wires of thesecond cable layer 60C are placed diagonally in the reverse directionrelative to the diagonal direction of the cable wires of the first cablelayer 60C so as to cross the cable wires of the first cable layer 60C.

FIG. 31 and FIG. 32 show two layers of the cable layers 60C, but threeor more layers of the cable layers 60C may be placed.

Further, the cable layers 60C embedded in the elastic solid 50 at onlyone side is illustrated, but they may be provided at both sides.

The operation in FIG. 31 and FIG. 32 will be explained.

A plurality of the cable layers 60C each having a different placementdirection of the cable wires are embedded near the end portion 40 b inthe longitudinal direction of the core 40, thus increasing rigidity inthe area near the portion where they are embedded. As a result, as inthe fifth embodiment, a crack does not occur at the elastic solid endportion 50 b, thus increasing durability of the elastic flat tread 3G.

As an application of the sixth embodiment, a plurality of the cablelayers 60C may be provided in the elastic flat tread 33 (See FIG. 17).For example, as FIG. 33 illustrates, in an elastic flat tread 33G, twolayers of the cable layers 60C are embedded inside the end portion 22 dof the elastic solid 22 under the end portion 11 h in the longitudinaldirection of the core 11. According to the above structure, as in theabove, durability of the elastic flat tread 33G is increased.

A seventh embodiment of the elastic flat tread will be explained withreference to FIG. 34 and FIG. 35.

In an elastic flat tread 3H, the core 40 is covered with and bonded tothe elastic solid 50 such as rubber as in FIG. 29. A plurality of cablelayers 60D are placed in parallel inside the elastic solid 50 and underthe core 40. FIG. 34 shows three layers of the cable layers 60D, butfour or more layers of the cable layers 60D may be placed. FIG. 34 showsonly one side of the elastic flat tread 3H, but as in the aforesaidembodiment, the cable layers 60D embedded in the elastic solid 50 may beprovided at both sides. Further, the length of the portion of the endportion 50 b of the elastic solid 50, which is protruded outward fromthe end portion 40 b, may be symmetric or asymmetric. The above isappropriately designed in consideration of the weights of various kindsof models small to large in size, the size of the elastic flat tread 3Hand the like. According to the above structure, as in the fifthembodiment, a crack does not occur at the elastic solid end portion 50b, thus increasing durability of the elastic flat tread 3H.

An eighth embodiment of the elastic flat tread will be explained withreference to FIG. 36.

An elastic flat tread 3I is formed by a core 70 covered with and bondedto an elastic solid 80 such as rubber. The elastic flat tread 3I isattached to the link 6 by bolts not illustrated being inserted into boltinsertion holes 80 c provided in the elastic solid 80. The core 70 iscovered with and bonded to the elastic solid 80 including an elasticsolid end portion 80 a on the side not in contact with the ground fromthe ground-contacting side to the side not in contact with the ground.Thereby, the elastic solid 80 is prevented from peeling away from thecore 70. The elastic solid 80 is integrally formed by elastic solidswith different hardnesses so that the hardness of the portion nearest tothe core 70 is the highest and the hardness lowers gradually toward theground-contacting side.

An elastic solid 80X forming the portion nearest to the core 70, anelastic solid 80Z forming the portion nearest to the ground-contactingside, and an elastic solid 80Y forming the middle portion between theelastic solid 80X and the elastic solid 80Z are respectively set at ahardness HS of 90, a hardness HS of 70, and a hardness HS of 80. Thehardnesses of the elastic solids 80X, 80Y, and 80Z are appropriately setaccording to the specifications such as the weights of various kinds ofmodels small to large in size, and the like.

The operation in FIG. 36 will be explained. The elastic solid 80 with ahigher hardness is strong against unbalanced load caused by defection orthe like, but provides poor riding quality and less abrasive resistanceon the other hand. Therefore, the elastic solid 80X nearest to the core70 is given the highest hardness. The hardness is sequentially loweredtoward the ground-contacting side, and the portion at theground-contacting side of the elastic solid 80 is formed by the elasticsolid 80Z with a lower hardness in consideration of riding quality andabrasive resistance. Consequently, even if the elastic flat tread 3Iruns on an protruding object such as a rock and stone, and a curb stoneof a sidewalk during traveling, a crack does not occur at an elasticsolid end portion 80 b, thus increasing durability of the elastic flattread 3I.

As an application of the eighth embodiment, the elastic solid 80 may beapplied to the elastic flat tread 33 (See FIG. 17). For example, as FIG.37 illustrates, the elastic solid 80 of an elastic flat tread 33I isintegrally formed by the elastic solids 80X, 80Y, and 80Z with differenthardnesses so that the hardness of the portion nearest to the core 11including the core end portion 11 h is the highest, and the hardnesssequentially lowers toward the ground-contacting side. According to theabove structure, as in the above, durability of the elastic flat tread33I is increased.

A ninth embodiment of the elastic flat tread will be explained withreference to FIG. 38.

An elastic flat tread 3J is formed by a core 93 being covered with andbonded to an elastic solid 90. The elastic flat tread 3J is attached tothe link 6 by bolts not illustrated being inserted in bolt insertionholes 90 c provided in the elastic solid 90. The elastic flat tread 3Jincludes a synthetic resin member 95 fixed to the elastic solid 90 nearan end portion in a longitudinal direction of the core 93. The syntheticresin member 95 is provided near one end portion in the longitudinaldirection of the core 93, or near both ends portions thereof.

The operation in FIG. 38 will be explained. If a material with a lowercoefficient of friction is used for the synthetic resin member 95 whichis fixed to the elastic solid 90, even if the synthetic resin member 95runs on a protruding object such as a rock and stone, and a curb stoneof a sidewalk, the rock or the stone slips and escapes therefrom,thereby making it possible to avoid local concentration of stress in thesynthetic resin member 95 and an elastic solid end portion 90 b. As aresult, a crack does not occur even if the elastic flat tread 3J runs onan protruding object such as a rock and stone, and a curb stone of asidewalk during traveling, thus increasing durability of the elasticflat tread 3J.

As an application of the ninth embodiment, the synthetic resin member 95may be applied to the elastic flat tread 33 (See FIG. 17). For example,as FIG. 39 illustrates, an elastic flat tread 33J includes the syntheticresin member 95 fixed to the elastic solid 90 near the end portion 11 hin the longitudinal direction of the core 11. According to the abovestructure, as in the above, durability of the elastic flat tread 33I isincreased.

A tenth embodiment of the elastic flat tread will be explained withreference to FIG. 40, FIG. 41, and FIG. 42.

In an elastic flat tread 3K, a core 100 is covered with and bonded to anelastic solid 110 such as rubber. The core 100 is formed of springsteel. According to the structure, even if the elastic flat tread 3Kruns on a protruding object during traveling, an end portion 101 in alongitudinal direction of the core 100 formed of spring steel isdisplaced upward, and thus local concentration of stress in an elasticsolid end portion 111 can be avoided. Though the end portion 101 of thecore 100 shown in FIG. 40 is formed to be flat, if the end portion 101of the core 100 is bent toward the side not in contact with the groundas in the first embodiment in FIG. 1, local concentration of stress inthe elastic solid end portion 111 can be further avoided. As a result,even if the elastic flat tread 3K runs on a protruding object duringtraveling, a crack does not occur in the elastic solid end portion 111,thus increasing durability of the elastic flat tread 3K.

An eleventh embodiment of the elastic flat tread will be explained withreference to FIG. 43 and FIG. 44.

An elastic flat tread 3L is formed by a core 115 covered with and bondedto an elastic solid 116. End portions 115 a and 115 b of the core 115are bent toward the side not in contact with the ground. Accordingly,the basic structure of the eleventh embodiment is the same as that inFIG. 1 of the first embodiment. What makes the structure of the eleventhembodiment different from the first embodiment is a point in which ametal plate 9A is attached (fixed) to a link 8 by welding or the like tobe integrated therewith, and the metal plate 9A is attached to the core115 with bolts 9.

According to the above structure, the end portions 115 a and 115 b ofthe core 115 are bent to the side not in contact with the ground, andthus local concentration of stress in the elastic solid end portions 116a and 116 b can be avoided as in the first embodiment in FIG. 1. As aresult, even if the elastic flat tread 3L runs on a protruding objectduring traveling, a crack does not occur in the elastic solid endportions 116 a and 116 b, thus increasing durability of the elastic flattread 3L. Further, the core 115 is attached to the link 8 with the metalplate 9A therebetween, thus making it unnecessary to provide boltinsertion holes in the elastic solid 116. As a result, problems such asa crack and peeling off resulting from the bolt insertion holes areeliminated.

As an application relating to the integration of the eleventhembodiment, the link and the core may be integrated. For example, FIG.45 shows integrated structure of the link 6 and the core 1 of theelastic flat tread 3A in FIG. 4. In an elastic flat tread 33A, the link6 is attached to a core 71 on the link mounting surface 6 a by welding.As a result, the formation of the bolt insertion holes 2 c provided inthe core 1 and the elastic solid 2 in FIG. 4 is eliminated and the boltsare made unnecessary.

As another example of the integration, it may be suitable to integratethe link 8, the metal plate 9A and the core 115 in FIG. 43. For example,in an elastic flat tread 33L in FIG. 46, the link 8, a metal plate 73,and a core 74 are attached to one another by welding to be integrated.As a result, the bolt insertion holes provided in the core 115 and themetal plate 9A in FIG. 43 are eliminated, and the bolts 9 are madeunnecessary.

Further, still another application of the eleventh embodiment will belisted.

(1) Any one of the cable layers 60A in FIG. 28, 60B in FIG. 29, 60C inFIG. 33, and 60D in FIG. 34 is placed inside the elastic solid 116 underthe core 115 and near the core end portion 115 b.

(2) The elastic solid 116 is integrally formed by the elastic solids80X, 80Y, and 80Z (See FIG. 37) with different hardnesses so that theelastic solid 116 has the same structure as the elastic solid 80 in FIG.37, and the hardness is the highest at the portion nearest to the core115 and sequentially lowers toward the ground-contacting side.

(3) The elastic solid 116 includes the synthetic resin member 95 fixedto the elastic solid 116 near the end portion 115 b in a longitudinaldirection of the core 115 (almost corresponds to the elastic solid endportion 116 b) so as to have the same structure as the elastic solid 90and the synthetic resin member 95 in FIG. 39. (4) The core 115 is formedof spring steel. (5) Further, the core 115 in the above items (1) to (4)is formed to be flat, specifically, to be in a form in which the coreend portions 115 a and 115 b are not bent.

A twelfth embodiment of the elastic flat tread will be explained withreference to FIG. 47 through FIG. 49. The elastic flat tread 33 issubstantially the same as the elastic flat tread 33 in FIG. 17 and FIG.18, and the core 11 other than the link mounting surface 6b is coveredwith and bonded to the elastic solid 22 such as rubber. The end portions11 a and 11 h in the longitudinal direction of the core 11 are benttoward the side not in contact with the ground. According to thestructure, as in the above embodiments, even if the elastic flat tread33 runs on a protruding object during traveling, a crack does not occurin the elastic solid end portions 22 a and 22 d, thus increasingdurability of the elastic flat tread 33.

A thirteenth embodiment of the elastic flat tread will be explained withreference to FIG. 50 through FIG. 52. In an elastic flat tread 83, acore 81 is covered with and bonded to an elastic solid 82 such asrubber. End portions 81 a and 81 b in a longitudinal direction of thecore 81 are bent toward the side not in contact with the ground.According to the structure, as in the above embodiments, even if theelastic flat tread 83 runs on a protruding object during traveling, acrack does not occur in elastic solid end portions 82 a and 82 b, thusincreasing durability of the elastic flat tread 83.

It goes without saying that the elastic flat treads according to thepresent invention described in detail thus far can be applied toconstruction equipment small to large in size as well as to endlesscrawler belts of industrial equipment, agricultural machinery and thelike other than the construction equipment.

Industrial Availability

The present invention is useful as an elastic flat tread which canprevent a crack from occurring in an elastic solid when the elastic flattread runs on or collides with an protruding object such as a rock andstone, and a curb stone of a sidewalk during traveling.

What is claimed is:
 1. An elastic flat tread for a crawler having atraveling direction; the tread comprising: links arrayed in thetraveling direction of the crawler and comprising link end portions;pins coupling the link end portions of adjacent links; and coresattached to respective ones of the links and covered with an elasticsolid at least on a ground-facing side thereof; said cores comprisingend portions that are bent, in a longitudinal direction, away from theground-facing side thereof; and wherein at least one of said cores on aside opposite the ground is covered with an elastic solid including anouter surface of the elastic solid which extends along the opposite sideparallel to said bent core end portions.
 2. The elastic flat tread inaccordance with claim 1, wherein at least one layer of cable layers isprovided inside said elastic solid, from a portion under the end portionin a longitudinal direction of said any core through a portion outsidethe end portion in the longitudinal direction of said any core.
 3. Theelastic flat tread in accordance with claim 2, wherein a direction inwhich cable wires of said cable layers are placed is the paralleldirection, or the combination of two directions or the parallel anddiagonal directions, relative to the longitudinal direction of said anycore.
 4. The elastic flat tread in accordance with claim 1, wherein saidelastic solid is integrally formed by elastic solids with differenthardnesses, in which the hardness at a portion in contact with said anycore is the highest and the hardness sequentially lowers toward theground-contacting side.
 5. The tread according to claim 1, wherein thecore is attached to the link by a metal plate which is attached to thelink.
 6. An elastic flat tread for a crawler having a travelingdirection; the tread comprising: links arrayed in the travelingdirection of the crawler and comprising link end portions; pins couplingthe link end portions of adjacent links; and cores attached torespective ones of the links and covered with an elastic solid at leaston a ground-facing side thereof; said cores comprising end portions thatare bent, in a longitudinal direction, away from the ground-facing sidethereof; and wherein the ratio between a height h, which is from amounting surface for said link up to a tip end in a height direction ofthe end portion in the longitudinal direction of at least one of saidcores, and a link pitch Lp is 0.05≦h/Lp≦0.25.
 7. The tread according toclaim 6, wherein the core is attached to the link by a metal plate whichis attached to the link.
 8. An elastic flat tread for a crawler having atraveling direction; the tread comprising: links arrayed in thetraveling direction of the crawler and comprising link end portions;pins coupling the link end portions of adjacent links; and coresattached to respective ones of the links and covered with an elasticsolid at least on a ground-facing side thereof; said cores comprisingend portions that are bent, in a longitudinal direction, away from theground-facing side thereof, and wherein the ratio between a height h,which is from a mounting surface for said link up to a tip end in aheight direction of the end portion in the longitudinal direction of atleast one of said cores, and a height H of the elastic flat tread is0.08≦h/H≦0.50.
 9. The tread according to claim 8, wherein the core isattached to the link by a metal plate which is attached to the link. 10.An elastic flat tread for a crawler having a traveling direction; thetread comprising: links arrayed in the traveling direction of thecrawler and comprising link end portions; pins coupling the link endportions of adjacent links; and cores attached to respective ones of thelinks and covered with an elastic solid at least on a ground-facing sidethereof, said cores comprising end portions that are bent, in alongitudinal direction, away from the ground-facing side thereof, andwherein the ratio between a width W1 of at least one of said cores and awidth W2 of a tip end in the longitudinal direction of the one of saidcores is 0.5≦W2/W1≦0.9.
 11. The tread according to claim 10, wherein thecore is attached to the link by a metal plate which is attached to thelink.
 12. An elastic flat tread for a crawler having a travelingdirection; the tread comprising: links arrayed in the travelingdirection of the crawler and comprising link end portions; pins couplingthe link end portions of adjacent links; and cores attached torespective ones of the links and covered with an elastic solid at leaston a ground-facing side thereof, said cores comprising end portions thatare bent, in a longitudinal direction, away from the ground-facing sidethereof; and wherein end portions of said elastic solid are protrudedoutward relative to the tip ends of the end portions in the longitudinaldirection of said core; and wherein at least one of said cores, on aside opposite the ground, is covered with an elastic solid including anouter surface of the elastic solid which extends along the opposite sideparallel to said bent core end portions.